1. Field of the Invention
This invention relates to grafted aramid fibers for improvement of adhesion between the fibers and rubber matrixes which the fibers are to reinforce. The aramid fibers are subjected to grafting while still containing water from the fiber manufacture.
2. Description of the Prior Art
U.S. Pat. No. 5,310,824, issued May 10, 1994, discloses poly(p-phenylene terephthalamide) fibers with fluoroalkyl groups grafted thereto and a process for performing the grafting reaction. The fibers are dry and there is no water in the grafting system.
Japanese Patent Publication (Kokai) 62-81426 published Apr. 14, 1987 and Japanese Patent Publication (Kokai) 62-91542, published Apr. 27, 1987 published Apr. 14, 1987, disclose a surface treatment of aramid by grafting reactions. The aramid can be poly(p-phenylene terephthalamide) fibers; but the reactions are anhydrous and dried fibers are used.
An article in The Journal of Adhesion Science, Volume 6, No. 12, pp. 1303-1323 (1992), titled "Wettability And Adhesion Studies Of Grafted Poly(P-Phenylene Terephthalamide) Fiber Surfaces", by Ravichandran and Obendorf, discloses that increased fiber-to-matrix adhesion can be obtained by grafting various materials onto the surface of fibers. The fibers are dry and the grafting reactions are free from water.